Safety device for a fuze



&73 9695 June 28, 1955 P. s. wLLAMs SAFETY DEVICE FOR A FUZE Filed ay 9, 1944 JGH F w H u m Y INVENTOR SAFETY DEVICE FOR A FUZE Philip S. Williams, Tulsa, Okla., assignor to the United SNtates of America as represented by the Secretary of the avy Application May 9, 1944, Serial No. 534,785

7 Claims. (Cl. 102--79) This invention relates to safety devices, particularly for use in conjunction with fuzes and related controlling means for projectiles.

An important object of the invention is to provide an improved safety device which is compact, rugged and foolproof in construction and positive in its action, and which, iurthermore, is easily manufacturable in Volume production at relatively low cost.

A related object is to provide such a safety device having relatively few parts, and in which a number of the parts are duplicates of one another, thereby simplifying manufacture.

Another object is to provide such a safety device having a pair of rotors, each rotor carrying a firing train portion which is movable, by rotation of the rotor, from a safe position of disalignment with respect to other portions of the firing train to an armed position of alignment with such other portions.

Another object is to provide such a safety device which is concentric in design and so constructed that it may be installed in a projectile without disturbing the dynamic balance thereof, and in which all portions of the firing train, when aligned upon arming of the device, lie upon the longitudinal axis of a projectile in which the device is installed.

Still another object is to provide such a device having a high degree of safety when unarmed and which is effectively and positively armed by the rotation imparted to the projectile during firing.

Other objects and advantages will be apparent from the following description taken in conjunction with the i.

drawings forming a part hereof, throughout the several views of which like reference characters are used to designate equivalent parts.

In the drawings:

Figure 1 is a plan view of a safety device constructed in accordance with the present invention, the cover plate thereof being removed and a portion being broken away, the parts being shown in unarmed positioning;

Figure 2 is a view similar to Fgure 1 but showing the parts in their armed position; and

Figures 3 and 4 are cross-sectional views taken on the lines 3-3 and 4-4 respectively of Figure 1, and looking in the direction of the arrows.

Referring now to the drawings, reference character J designates the substantially cylindrical casing of my improved safety device, which may be provided with eX- ternal threads (undesignated) by which it is adapted to be positioned in the projectile in properly aligned relationship with respect to the rest of the fuzing and detonating Components thereof. Such other Components may be of conventional or any desired construction, and, forming no part of the present invention, are not illustrated. It will be understood that the axial apertures P, Q, the former in the integral bottom of the casing J, and the latter in the cover plate S, are aligned with and form a part of the firing train, the explosion initiated by the priming means (also unshown) being required to travel ntecl States Patent- "ice through these, as well as through the interior mechansm of the safety device, in order to detonate the projectile.

Fitted in the cylindrical interior of the casing J is cylindrical body H, which is eccentrically counterbored from its opposite ends to receive the rotors A, A' rotatable upon their respectve shafts D, D' fitted into the body and suitably projecting centrally into the counterbores. The rotor axes lie on a diametral plane of the casing J and body H. An axial firing train opening R is for-med in the web portion of the body between the overlapping counterbores therein which house the rotors A, A' and firing train holes G, G' are also formed in the rotors, in such positions that the rotors may be rotated to bring the holes G, G' into registry with one another and with the previously mentioned firing train openings P, Q, R, to form a continuous passage through which the explosive wave may travel to detonate the projectile.

Rotation of the discs or rotors A, A' is limited by stop pins E, E', each of which, mounted in the body H, projects into a peripheral notch B, B' in the periphery of its disc.

Each rotor is also provided with a weighted section F, F', which may be formed by filling a hole therein with lead or other suitable material which is heavier than the rest of the rotor. When the rotors are in their unarmed positions (shown in Figure 1) their firing train openings G, G' are disaligned with respect to the fixed firing train apertures P, Q, R, and the Weighted sections F, F' are in such positions that rotation of the projectile, and the centrifugal force developed thereby, will tend to throw the weighted sections outwardly and turn the rotors in the directions required to align the several firing train openings. The stop pins E, E' and slotted sections B, B' are so positioned that movement of the rotors is arrested with the firing train openings in their axial position of registry, as shown in Figure 2. As also indicated in the last mentioned View, the weighted sections are arrested before they have reached positions lying on a diameter projected through the spindles D, D' and the axis of the projectile. The weights therefore continue to exert posi tive outwardly directed force, maintaining the firing train openings in alignment until firing has occurred. The rotors are retained in the disaligned, safe position of Figure l by detents K, K' mounted in the body H. One such detent engages a notch in each rotor. A fiat leaf spring as L, L', behind each of the detent pins K, K' tends to project the pin inwardly with respect to its rotor, thereby firmly holding the latter against the rotation. lt will be seen that the ettect of centrifugal force resulting from the spin of the projectile tends to cause the detents to move outwardly. The design of the Components is such that the spin imparted to the projectile by the rifling is suificient to disengage the detents from their notches and turn the rotors to the armed position.

It is desirable to prevent arming until after the projectile has left the gun, regardless of the rotational velocity achieved in the bore. Arming in the bore is prevented by the frictional engagement which occurs, as a result of set-back, between the bottoms of the rotors and the chambers in which they are fitted. in order to insure that this braking action will be efiectively exerted near the periphen'es of the rotors, each rotor is provided with a rim M projecting downwardly against the bottom of its rotor chamber. The rim M is urged against the bottom of the chamber with great force during accele'ation of the projectile, the rotors being thereby effectively prevented from turning until the projectile has left the gun.

It is a feature of the design that the weighted sections F, F' are so placed that the resulting center of mass of each rotor lies on a radius of the rotor which makes an angle of approximately 90 with the line of motion of the corresponding detent, on the same side of said line as the weighted section, when the rotor is in the unarmed position. As a result of this arrangement, rotation of the projectile about the axis of the assembly tends to free the detents, but if the projectile is struck or subjected to any other iateral inertial force, as for example during handlng or at any other time prior to firing, such force, if it tends to cause retraction of a detent from its rotor, also tends to rotate the rotor toward and hold it more firmly in the unarmed position. The reverse is also true,

viz; if the lateral force tends to rotate the rotor toward armed position, the detent is by that same force projected more firmly into the holding position.

e Iclaim:

1. A safety device of the character described comprising a substantially concentric body having a plurality of eccentric overlapping substantially cylindrical chambers therein, rotors adapted to revolve in said chambers, the axes of revolution of the rotors being eccentric but substantially parallel to an intermediate axis of the assembly and to the spin axs when the device is installed, said rotors having firing train portions movable by turning of the rotors on their axes to bring such portions into alignment with said intermediate axis and with one another, thereby establishing an armed condition, each of said rotors being overweighted on one side in such manner that it tends to turn in a direction to establish said armed condition When the entire assembly is rotated about said intermediate axs, and centrifugally releasable detent means restraining unwanted turning of said rotors.

2. In combination with means as set forth in claim i, supplemental holding means operable by set-back to prevent turning of said rotors to armed position during linear acceleration of the device in the bore of a rifle regardless of the rotational velocity achieved during such linear acceleration.

3. Means as set forth in claim l in which said rotors are symmetrically disposed about said intermediate axis to maintain the dynamic balance of the assembly portions of said rotors overlapping said intermediate axis and one another, detent means being provided for each rotor including a portion lying on the opposite side of the intermediate aXis from the overweighted portion of said rotor and movable outwardly away from such axis, to release the detent means, in a direction opposite to that in which the overweighted portion moves in turning the rotor to armed position.

4. Means as set forth in claim 1 in which portions of said rotors overlap and said intermediate axis extends through the overlapping portions, detent means being provided for each rotor including a portion lying on the op- 'posite side of the intermediate axis from the overweighted portion of each rotor being movable outwardly away from such axis, to release the detent means, in a direc- 4 j V tion opposite to that in which the overweighted portions move in turning the rotors to armed position, means arresting rotation of said rotors when the firing train portions thereof are in registry and before the overweighted portions have reached radal alignment with respect to the spin axis and the rotor axes, whereby the rotors are positively held in their armed positions by such overweighted portions. r

5. Means as set forth in claim l in which two such chambers are provided, of reentrant form,.extending ;inwardly from opposite ends :of the body, means for rctaining the rotors in the chambers, and means for monnti-ng the body in substantially coaxial relation in .a projectile.

6. In a fuze unit for a high explosive projectile, the combination with a casing having two spaced axialiy aiined fuze openings and two diametrically arranged, overlappng chambers, each of said chambers having a centrifugally operated rotor pivotally mounted .therein, each of said rotors being provided with' a fuze portion,

\ a friction rim on the rear face of each rotor operable under force of setback for braking coaction with the cas'- ing, spring-pressed detents engaging the rotors and retractable under centrifugal force to free the rotors, and means for'limiti'g arming movement of the' rotors.

7. In a fuze unit for a high explosive projectile, the combination with a casing having a p'lurality of eccentric overlapping chambers therein, a plurality of rotors adapted to revolve in said chambers, the axes of revolution of said rotors being 'eccentric 'but 'substantialiy par: allel to an intermediate axis of the assembly and to'the spin axis when the unit is installed, said rotors having firing train portions movable by rotation of' said rotors into alinement with said intermediate axs and with one another, each of said rotors being overwe'ighted on one side to cause said rotors to rotate when the entire assembly is rotated about said intermediate axis, a friction rim on the rear face of each of said rotors operable under force of setback 'for braking coactionwith the casing, and centrifugally releasable detent means restraining undesirable rotation of said rotors.

References Cited in the file -of this patent UNITED STATES PATENTS l,172,637, Semple Feb. 22, 1916 1,383,751 Pillars et al July 5, 1921 1,561,687 Brayton Nov. 17, ,1925 1,688,652 Pearson ..-i Oct. 23, 1928 .1,7 15,513 Rogers June 4, 1929 2,594,340 Q'Rear i Apr. 29, 1952 FOREIGN PATE-NIS 227,423 Germany Oct. 21 1910 

